More countries have pledged ambitious net-zero targets. Thus, the extent to which CO2 removal (CDR) is needed to achieve these targets may become greater. However, only a limited range of CDR technologies are represented in the integrated energy-economy models (IAMs), thus limiting the capability of IAMs to provide guidance on feasible options to achieve such targets fairly. For instance, most scenarios in IAMs require a significant CDR to take place in developing regions while their capability to implement this might be limited. Although technical and political aspects have been generally considered in the models, there is a lack of socio-political transitions feasibility and fairness analysis to bridge the gap between the current status and future pathways of the 1.5oC goal of the Paris Agreement.

To quantify the role of novel CDR technologies to climate mitigation pathways, Direct Air Capture of CO2 with Storage (DACCS) technologies, both high and low temperatures representations, are included as the archetype. This is because of DACCS readiness and potential to provide significant capacity of CDR with potentially less impact on other sustainable development priorities. Institutional capacity, that is the capability to implement environmental policies, regulations, and legislation is critical to keep warming well below 2°C, is represented in our model framework as a CO2 emissions reduction constraint for each region, using GDP per capita, gender equality and levels of education as the main predictors.

We find that the impact of DACCS on the feasibility and fairness of overall mitigation efforts depends strongly on the desired climate outcome. In the 2°C scenarios, DACCS allows lower CO2 removal deployment in developing regions, relieving the regions from demanding mitigation requirements. However, the short-term impact of DACCS is negligible if a more ambitious climate outcome, i.e., the 1.5oC scenarios, is pursued. This becomes more prominent in scenarios where institutional constraints are considered. In this context, unrealistic assumptions on DACCS growth are required; implying near-term gross emissions reductions and financial and technological support to developing countries cannot simply be substituted by large-scale novel CDR deployments in developed countries. This highlights the necessity of enhancing institutional capacity in 1.5°C pathways while maintaining the feasibility of keeping the warming to well below 2°C if new forms of CDR fail to materialize. Notwithstanding this, novel CDR technologies are essential to allow more equitable post-net-zero CO2 mitigation efforts.

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